Telescope-spectacle glass.



--vvlil M. VON ROHR. TELESGOPB SPEGTAULE GLASS. APPLIOATIOH zum: 1srov.za. 1911.

Patefited June 4, 1912.

UNITEI) STATES PATENT OFFICE.

MORITZ von ROHR, OF JENA, GERMANY, ASSIGN'OR T0 TEE FIRM OF CARL ZEISS, DIE JENA, GERMANY.

TELESCOIPE-SPECTACLE GLASS.

T0 all wh0m z't mag oonoern:

Be it known that I M0RITZ VON ROHR, a citizen of the Gerrnan -Empirei residing at- Jena, Germany, have invented a new und useful Telescope-Spectacle Glass, of which the following is a specification.

The subject 0f the invention is a lens-system for teiescope-spectacles (a telescopespectacle-glass), presenting a very large field of Vision und exhibiting, even when objects at the margin of this field are viewed, therefore even for the pencils of greatest inclination, a very sr'na1l a1nount of distortion, a moderate chromatic aberration and only traces of astigmatism. Telescope-spectacle-glasses are known, besides from other sources, from the Patent 1000346. They are, along with the Galileani escppesin restricted sense, wsiih-species of the telescopesystem consisting of a. collective front rnembei und a dispersive hinder mernber. The Weight of a telescope-spe0tacle-glass, the distance between its two members und the distance of its center of' gravity frorn the hinder mernber must be small. Therefore its magnification is et most a twofold one, und its objective is not achromatized, but consists of asingle collective lens. -By means of the connection of the telescopespectacleglass with the users head the condition, which is the usual start-ing point in the Calculation of spectacle-glasses, is fulfilled in practice, viz. that the center of the diaphragm of the system, the crossing-point- 01: the principal rays, lies in the locus of the center of rotation of the eye, approximately 2:}- cm. behind the rezir lens surface. F01 this reason it is possible with the telescopespectacle-glass to ut-ili2e in n perfect manner a, very extensive fie1d of vision, presenting a sharp ilnage up to its margin, while an adjustment bet-ween the two members for adapting the system to the refractive Condition of the eye of the observer is excluded. The fixed distance between the 1nembers may be chosen in such a manner, that a telescope-system in the strict sense 0f the term results. The power of this system is zero, so that it is suitable for an ennnetropic eye. The systern may, 011 the other band, have a moderate negative or positive vertex refraction, so as to be suitable for a rnyopic 01 a hypermetropic eye of corresponding axial refraction for the purpose of directly and distinct-ly seeing distant objects.

Speciflcation of Letters Patent.

Application filed November 22, 1911.

Patented J 11118 4, 1912.

Seria1 N0. 661,839.

In the telescope-spectacle-glass according to the present invention a chromatic correct1on is attained in the s:nne manner zus in the case of the lens-system for Galilean telescopes, described in the Gerrnan Patent 20729. The chromatic aberration of the sing1e collective front member is partly compensated by the dispersive hinder rnember, which is cemented together out of a collective lens and a dispersive one. F01 this purpose there is chosen for the collective lens a glass of a lower refractive index und for the dispersive lens one of a higher relative dispersion. In order t0 counteract the astigmatism of the inciined pencils und at the same time reduce the distortion to a, small amount, the dispersive lens is to be disposed, according to the present invention, es the hinder 1ens and in a bi-concave form. WVith this arrangement a particularly extensive correction of astigmat-ism may t-hen be obtained, if the collective front lens be given a concave front surface, so that the hinder Inember receives a bLconcave form.

If the eye, which is to be fitted with the neW telescope spectacle glass having two mernbers, be afflicted with astigrnatism, this ocular defect rnay be corrected by converting one of the free lens surfaces of the systern, which latter has been caiculated in the ordinary way, from a spherical to a toric one, of the two radii of which one deviates in the direction and amount, requisite for the correction, from that of the former spherical surface. In order to let the axial astigmatisnn thus introduced appear on all principal rays of finite inclinat-ion as weil, the rear surface of the system may be made the toric one. T0 still better attain this object, the rear spherical surface may be further selected in such a manner, that it perrnits the principal rays to ern6rge without deflection 01 with only a slight deflection. That is the case, when its center lies very near the crossing-point of the principal mys, so that its radius keeps between the limits 20 und 35 nun.

In the annexed drawing: Figure 1 is a, constructional form of the spectacleglass according to the invention, suitable for an emrnetropic eye. Fig. 2 is a second form 0f such a spectacle-glass, suitable for a myopic eye. F ig. 3 is a third form of such a spectacle-glass, suitable for a hypermetropic eye. In all three cases the rear surface of the system realizes the condition last made,

while, the eye being assumed to be free frorn astigmsitism, the rear surface is left spheriaal, as the conversion of this surface into a 5 toric one requires 110 explanation.

First example (Fz'g. I).

Te1esco ic lens-system (for emmetropic eyes). agnification of the retinal image in the axia1 direction 1.77. Below are given: the dimensions 0f the lenses I, II and IIItheir distances apart and from the crossing-poinc O 01. the principal rays, the inclinations w and 'll/max 0f the marginal principal rays 0n entering and emerging, the kinds of glass and also the remaining portions of astigmatism. These remaining portions are illustrated by the reciprocals measured in dptr. 0f the intersectional distances sfand s on the side nearest the eye gf the sagittal and meridional pen cils whi ch pertain to the principal ray coinc1ding w1th the axis, to one of intermediate inclination and t0 a marginal principal ray.

Dimensions und distances of the lenses in mm.

d -8.5; b118; (i -1.5; d =0.5; Z-25 1 :20,6; n=250; r;=40.6; 14=15.0; 1 =29.3 D =33.6; D =15.8; D =13.S Inclination of entrance und emergence of the marginal prinmpal rays.

Second ewample (Fz'g. 2).

Lens-system of 7 dptr. verteX refraction (for myopic eyes 0f 6.5 dptr. axial refraction). Magnification of the retinal image 1.80.

Dimensions and distances of the lenses in mm. d.=s.o; b=l6.5; d =l.9; d =0.; l=25 n=-25.5; n=239; 1' =51.73 n=19.0; n=26.7 DI=86.3; D=15.2; D =13.0

Inclination of entrance und emergence of the margi1ial Thz'ra? eaeample (Fz'g.

Lens-system 0f +3.4=4 dptr. Vertex refraction (f0r hypermetropic eyes 0f 3.57 dptr. axial refraction). Magnification 0f the retimal image 1.91.

+3.22 dptr.

I claim:

l. Achromatic telescope-spectacle-glass of ab the most a twofold magnification, comsisting of a single, collective front member and a dispersive hinder member, which latter is cemented together out 0f a collective lens of a lower refractive index and a dispersive lens of a higher relative dispersion, the dispersive lens being the hinder lens of the hinder member and bi-concave.

2. Achromatic telescope-spectacle-glass of at the most a twofold magnification, consisting of a single, collective front member and 95 a dispersive hinder member, which latter is cemented together out of a collective lens ofa lower refractive index and a dispersive lens of a higher relative dispersion, the hinder member being bi-concave and the dispersive lens being the hinder lens of t-his member ancl bi-concave.

3. Achromatic telescope-spectacle-glass 0I' als the most a twofold magnification and suitable f0r an astigmti eye, consisting 0f 3 a Elnglia,"llbffifront member and a dispersive hinder member, which latter is cemented together out 0f a collective lens 0f a lower refractive inclex and a clispersive lens 0f a higher relative dispersion, the hincler mernber being bi-concave, the dispersive lens being the hinder 1ens 0f this member and bi-concave, the hinder surface of this hinder member being f'or the correction of the said asigmatisrn a i :oric on e and one of'fhi' twb radi'1 01 the tdrid surfae lying between 20 and 35 mm.

MORITZ VON ROHR.

Wit1 1esses PAUL KRGER, FRITZ SANDER.

Copies 01 this patent may be obtained tor fiyre eents each, by addressing the Oommissioner o! Patents, Washington, D. G. 

